The objective of this proposal is an immunogenetic study of the H-Y antigen. We hope to provide a basis for the future use of this sex-linked marker in clinical diagnosis and to gain an understanding of the role of H-Y in primary sex differentiation. This study centers around the use of monoclonal anti-H-Y antibody produced in our laboratory. These antibodies have the same specificity as conventional anti-H-Y antisera, but are of higher titers. Our preliminary results show that the murine monoclonal anti-H-Y antibody crossreacts with human H-Y, making it feasible to perform H-Y typing on cells of human subjects wth structurally modified Y chromosomes. We propose to: (1) develop radiobinding and fluorescence assays for routine clinical use which would identify Y chromosomal genes in invdividuals with ring or minute sex chromosomes, and to perform H-Y typing assays using human amniotic cells; (2) quantitate H-Y antigen on cell surfaces and study the correlation between quantity of H-Y antigen and testicular development; (3) isolate and biochemically characterize H-Y antigen; (4) clarify wether there is polymorphism of H-Y antigen as recognized by antibody, cell-mediated cytolysis and skin transplantation; provide the basis for immunoselection of Y-bearing sperm; (6) test the hypothesis that H-Y acts as an inducer in testicular differentiation.